LCWS 05 1

Experimental studies of Strong Electroweak Symmetry Breaking

in gauge boson scattering and

three gauge boson production

P.Krstonosic

Work done by : K. Mönig, P.Krstonosic, M. Beyer, E. Schmidt, H. Schröder

LCWS 05 2

Introduction

ee ee 4 5 6 7 10

WWWW WWWW + +

ZZWW + + + +

ZWZW ZWZW + + + +

ZZZZ ZZZZ + + + + +

• deff. remark

• All possible weak boson scattering processes and sensitivity to the quartic anomalous couplings

VVtrVVtrL 24

4 16

LCWS 05 3

Processes

Channel ee

qqqqWW eeee

qqqqZZ eeee

)(backgroundqqqq

qqqqeZWe

qqqqeeWWee

qqqqeeZZee

Xtt

qqqqWW

qqqqZZ

qqeWe

qqeeZee

qq

Channel ee

qqqqWW eeee

qqqqeZWe ee

qqqqeeWWee

qqqqeeZZee

qqeWe ee

qqeeZee

Xttee

• Polarization 80%L for e- , 40%R for e+ for the beams

new

• Initial state radiation taken into account • single weak boson production as background • e- e- option considered

LCWS 05 4

• dependence of the total cross section on anomalous couplings( only one varied at a time) , and sensitivity of variables used in the fit ( total mass , absolute production and decay angle )

Sensitive variables

LCWS 05 5

• Matrix element calculation with

lkji

MClkji

lkji

MClkji

DATAlkji NNNL )log(

jiijiiji EDCBAR 221),(

Simulation & Fit• Full 1ab-1 event sample generated with

WHIZARD

• Hadronization with PYTHIA followed by SIMDET fast simulation O'mega used for calculating

event weights in the form :

where R is the ratio of the matrix element to the SM one • Sensitivity is evaluated with Binned Likelihood Fit

DATAN SM sample, RNN DATAMC • After separate analysis for signal processes double counted events were assigned to one sample according to mass distance from M(V)+M(V) mass (V=W or Z)

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ISR

• example of ISR influence on result

( 800GeV W+W- )

Fit for only signal process

( no background)

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• reconstructed mass distribution for W (blue) and Z (red) at 1TeV (Durham)

Analysis

ZWeee

• polar angle of final state lepton 30% reduction within detector acceptance when going from 0.8->1TeV

1TeV

800GeV

LCWS 05 8

Analysis

allb-tagg

• realistic anti b-tagging used ( ZVTOP ) for WW signal

• significant reduction of Z contribution in a W mass window possible ( 50% within 70-85GeV as marked on the picture )

LCWS 05 9

800GeV e+e-

• comparison with R. Chierci, S, Rosati, M. Kobel LC-PHSM-2001-038

• our result in red , old in black • full line 70%Cl dotted 90%Cl

LCWS 05 10

800GeV e+e-

combined• result from 1ab-1

sample

• change in estimated limits mainly from difference in WW->ZZ limit.

LCWS 05 11

1TeV gain

• Improvement in result by going from 800GeV (in green) to 1TeV (in red)• Combined effect of : - signal cross section rise

- s-channel background reduction - rise of effective rescattering energy

LCWS 05 12

1TeV e+e-

• two parameter contours

( full line 70%Cl, dotted line 90%Cl)

LCWS 05 13

1TeV e+e-

• Results from 1ab-1 sample• 2D case ( ) 01076 • and a full 5D fit

LCWS 05 14

1TeV e+ e-

2D 1σ Error

1.41 1.38

1.16 1.094

5

5D 1σ Error

-2.72 2.37

-2.46 2.35

-3.93 5.53

-3.22 3.31

-5.55 4.55

4

5

6

7

10

• result for a 1ab-1 sample from e+e- processes at 1TeV

LCWS 05 15

1TeV e-e- and combined

•in red 1ab-1 e+e- & 350fb-1 e- e-

•in blue 2ab-1 e+e-

LCWS 05 16

standard modelbackground

Feynman diagrams e+e_W+ W_ Z

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• momenta• 3 particles x 4 components12• energy momentum conservation - 4 • on-shell condition - 3• axial invariance (-dependence) - 2

– e.g. eZ plane, ZW plane• total 3• kinematical variables:

• spins, 2 d.o.f•

( ), ,WZ WWZ

Mp

M Zqe.g. beam vs. r^

, , ,...,LLT LTL TTTLLLs s s ss:

Three-body kinematics

LCWS 05 18

• Discretize observable into bins Nijk

• Ntheo Whizard – with n = 2 Mio evts.

• Nexp (Simdet Pythia) Whizard– with L = 1000 fb-1

( ), , " , , "WZ WWi j k M M Zq=

efficiency 60% purity 70%

Sensitivity

15

1.,2

2exp2

kji ijk

theoijkijk NN

LCWS 05 19

5

4

preliminary

Confidence level contours

70%Cl 90%Cl

WWZ 80% e-right, 60% e+left ZZZ unpolarized

WWZ 80% e-right polarizationWWZ unpolarized

LCWS 05 20

Summary

• Major step towards a full and consistent set of limits done

• Confirmed cutoff scale reach above 2.5TeV for isospin conserving case

• Triple weak boson production still to come

• Interpretation of results in specific physic scenarios in plan

ii

TeV

3